revert force-set of CORS header on cache misses

Makefile

@@ -76,8 +76,8 @@ up:
 .PHONY: down
 # stop the service and it's dependencies
 down:
-	rm docker/shared/genesis.json
-	rm docker/shared/VALIDATOR_NODE_ID
+	rm docker/shared/genesis.json || echo no shared genesis present
+	rm docker/shared/VALIDATOR_NODE_ID || echo no shared validator node id present
 	docker compose down
 
 .PHONY: restart

ci.docker-compose.yml

@@ -22,7 +22,7 @@ services:
       dockerfile: ci.Dockerfile
     env_file: .env
     environment:
-      PROXY_HEIGHT_BASED_ROUTING_ENABLED: true
+      PROXY_HEIGHT_BASED_ROUTING_ENABLED: "true"
       # use public testnet as backend origin server to avoid having
       # to self-host a beefy Github Action runner
       # to build and run a kava node each execution

main_batch_test.go

@@ -225,8 +225,10 @@ func TestE2ETest_ValidBatchEvmRequests(t *testing.T) {
 			// check expected cache status header
 			require.Equal(t, tc.expectedCacheHeader, resp.Header.Get(cachemdw.CacheHeaderKey))
 
-			// verify CORS header
-			require.Equal(t, resp.Header[accessControlAllowOriginHeaderName], []string{"*"})
+			// verify CORS header (only on cache hits. cache misses return the backend value, if set)
+			if tc.expectedCacheHeader == cachemdw.CacheHitHeaderValue {
+				require.Equal(t, resp.Header[accessControlAllowOriginHeaderName], []string{"*"})
+			}
 
 			// wait for all metrics to be created.
 			// besides verification, waiting for the metrics ensures future tests don't fail b/c metrics are being processed

main_test.go

@@ -525,7 +525,7 @@ func TestE2ETestCachingMdwWithBlockNumberParam(t *testing.T) {
 			expectKeysNum(t, redisClient, tc.keysNum)
 			expectedKey := "local-chain:evm-request:eth_getBlockByNumber:sha256:d08b426164eacf6646fb1817403ec0af5d37869a0f32a01ebfab3096fa4999be"
 			containsKey(t, redisClient, expectedKey)
-			require.Equal(t, cacheMissResp.Header[accessControlAllowOriginHeaderName], []string{"*"})
+			// don't check CORs because proxy only force-sets header for cache hits.
 
 			// eth_getBlockByNumber - cache HIT
 			cacheHitResp := mkJsonRpcRequest(t, proxyServiceURL, 1, tc.method, tc.params)

service/batchmdw/batch_processor.go

@@ -109,7 +109,7 @@ func (bp *BatchProcessor) applyHeaders(h http.Header) {
 		// clear content length, will be set by actual Write to client
 		// must be cleared in order to prevent premature end of client read
 		bp.header.Del("Content-Length")
-		// clear cache hit header, will be set by flush()
+		// clear cache hit header, will be set by RequestAndServe()
 		bp.header.Del(cachemdw.CacheHeaderKey)
 	}
 

service/middleware.go

@@ -100,7 +100,7 @@ func createDecodeRequestMiddleware(next http.HandlerFunc, batchProcessingMiddlew
 
 		// skip processing if there is no body content
 		if r.Body == nil {
-			serviceLogger.Trace().Msg("no data in request")
+			serviceLogger.Trace().Msg("no data in request body")
 			next.ServeHTTP(w, r)
 			return
 		}
@@ -119,6 +119,13 @@ func createDecodeRequestMiddleware(next http.HandlerFunc, batchProcessingMiddlew
 		// Repopulate the request body for the ultimate consumer of this request
 		r.Body = io.NopCloser(&rawBodyBuffer)
 
+		// skip processing if body is empty
+		if len(rawBody) == 0 {
+			serviceLogger.Trace().Msg("no data in request body")
+			next.ServeHTTP(w, r)
+			return
+		}
+
 		// attempt to decode as single EVM request
 		decodedRequest, err := decode.DecodeEVMRPCRequest(rawBody)
 		if err == nil {
@@ -263,7 +270,7 @@ func createProxyRequestMiddleware(next http.Handler, config config.Config, servi
 						w.Header().Set(headerName, headerValue)
 					}
 				}
-				// add CORS headers (if not already added)
+				// cached requests should have CORs set, but if they don't, default to configured value.
 				accessControlAllowOriginValue := config.GetAccessControlAllowOriginValue(r.Host)
 				if w.Header().Get("Access-Control-Allow-Origin") == "" && accessControlAllowOriginValue != "" {
 					w.Header().Set("Access-Control-Allow-Origin", accessControlAllowOriginValue)
@@ -281,11 +288,6 @@ func createProxyRequestMiddleware(next http.Handler, config config.Config, servi
 					Msg("cache miss")
 
 				w.Header().Add(cachemdw.CacheHeaderKey, cachemdw.CacheMissHeaderValue)
-				// add CORS headers (if not already added)
-				accessControlAllowOriginValue := config.GetAccessControlAllowOriginValue(r.Host)
-				if w.Header().Get("Access-Control-Allow-Origin") == "" && accessControlAllowOriginValue != "" {
-					w.Header().Set("Access-Control-Allow-Origin", accessControlAllowOriginValue)
-				}
 				proxy.ServeHTTP(lrw, r)
 			}